利用非平衡热力学建立玉米镉积累模型

IF 5.4 Q1 PLANT SCIENCES

Current Plant Biology Pub Date : 2024-07-02 DOI:10.1016/j.cpb.2024.100369

Christian Moyne , Pierre Leglize , Thibault Sterckeman

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引用次数: 0

摘要

世界上有许多人因食用植物产品而过量接触镉。一个能预测作物中镉含量的模型将改善风险评估和文化实践。由于目前还没有这样的模型，我们评估了不同的方法来模拟玉米根部对镉的吸收及其向气生部分的转移。利用非平衡热力学，我们认为镉从一个区室（A）到另一个区室（B）的通量（JA,B）与区室之间的电化学势之差成正比，并由 JA,B=βA,Bln(KBCA/KACB) 型方程给出，其中 βA,B 和 KB 是常数，CA 和 CB 是区室 A 和 B 中的实际镉浓度。考虑的分区包括根圈溶液（Rh）、根皮层（Co）、木质部汁液（X）和气生组织。根据玉米在根圈溶液中恒定的镉浓度下暴露 8 小时对镉的吸收实验，对该模型进行了评估。该模型可以描述镉从根圈到根皮层的流动，βRh,Co = 8.7E-11 mol m-2 s-1 和 KCo = 73。这就对通常使用 Michaelis-Menten 动力学来模拟根系的长期吸收（整个栽培期）提出了质疑。在这种情况下，Michaelis-Menten 吸收动力学的表面有效性可能与根的生长而不是镉的内化机制有更密切的关系。考虑到穿过根皮层对离子传输的阻力，必须将热力学和扩散形式联系起来，这样才能预测木质部的镉通量（KX = 12.48，扩散系数 DCo = 3.44E-11 m2 s-1）。通过模拟植物蒸腾作用产生的液流，可以更好地预测从木质部到气生组织的镉通量。这项工作为建立相对简单的植物镉积累模型开辟了前景。

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Using non-equilibrium thermodynamics to model cadmium accumulation by maize

Many people around the world are overexposed to cadmium through their consumption of plant products. A model predicting Cd content in crops would improve risk assessment and cultural practices. As no such model exists, we evaluated different methods to simulate the root uptake of Cd and its translocation to the aerial parts of maize.

Using non-equilibrium thermodynamics, the Cd flux ( $J_{A, B}$ ) from one compartment (A) to another (B) was considered to be proportional to the difference in electrochemical potential between the compartments and given by an equation of the type $J_{A, B} = β_{A, B} \ln (K_{B} C_{A} / K_{A} C_{B})$ , where $β_{A, B}$ and $K_{B}$ are constants and $C_{A}$ and $C_{B}$ the actual Cd concentrations in compartments A and B. The compartments considered were rhizosphere solution (Rh), root cortex (Co), xylem sap (X) and aerial tissues. The model was evaluated against the experimental uptake of Cd by maize exposed for 8 h to a constant Cd concentration in the rhizosphere solution.

The formalism made it possible to describe the flow of Cd from the rhizosphere to the root cortex, with $β_{Rh, Co}$ = 8.7E-11 mol m⁻² s⁻¹ and $K_{Co}$ = 73. This questions the common use of Michaelis-Menten kinetics to model root absorption over the long term (throughout the cultivation period). In this case, the apparent validity of the Michaelis-Menten uptake kinetics is probably more closely linked to the root growth than to the Cd internalization mechanisms. To take into account the resistance to the ion transport linked to crossing the root cortex, thermodynamic and diffusion formalisms had to be associated, which enabled the prediction of the Cd flux towards xylem, with $K_{X}$ = 12.48 and a diffusion coefficient $D_{Co}$ = 3.44E-11 m² s⁻¹. The Cd flux from xylem to aerial tissues was better predicted by modelling the sap flow due to plant transpiration. This work opens perspectives towards a relatively simple modelling of plant Cd accumulation.

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来源期刊

Current Plant Biology Agricultural and Biological Sciences-Plant Science

CiteScore

10.90

自引率

1.90%

发文量

审稿时长

50 days

期刊介绍： Current Plant Biology aims to acknowledge and encourage interdisciplinary research in fundamental plant sciences with scope to address crop improvement, biodiversity, nutrition and human health. It publishes review articles, original research papers, method papers and short articles in plant research fields, such as systems biology, cell biology, genetics, epigenetics, mathematical modeling, signal transduction, plant-microbe interactions, synthetic biology, developmental biology, biochemistry, molecular biology, physiology, biotechnologies, bioinformatics and plant genomic resources.